With respect to processes for the production of paraffins, olefins and aromatic hydrocarbons, various techniques have been investigated which include not only processes of cracking petroleum, but also processes which use, as raw materials, methanol and dimethyl ether obtained from a hydrogen/CO mixed gas that in turn is obtainable by modifying natural gas by using a new energy source. Especially, in more recent processes that have been developed, in comparison to older known processes, the products obtained contain substantially no sulfur compounds and are thus expected to be environmentally-friendly petrochemical raw materials.
Such processes for producing paraffins, olefins and aromatic hydrocarbons by using methanol and dimethyl ether as raw materials, are usually named, depending upon the types of the main products produced. That is, a process in which gasoline is obtained as the main product is referred to as the MTG process, and a process by which lower olefins, as the main products, is referred to as the MTO process. A process of producing propylene, in particular, of the lower olefins, as the main component, is referred to as the MTP process.
However, in a case where propylene is obtained from methanol (see e.g. Patent Documents 1 to 3), theoretically, one molecule of propylene will be formed from three molecules of methanol. However, the yield of propylene product, based on the molar amount of the raw material methanol, is only 33% at maximum. Moreover, the weight of water that is formed as a by-product is substantial. Accordingly, such a process can not be regarded as a preferred industrial process from the viewpoint of e.g. the efficiency of installation costs.
On the other hand, with regard to the MTP process, it is also known that propylene is obtained from ethylene and methanol (non-Patent Document 1). However, in this process, the yield of propylene based on the amount of raw material methanol does not exceed 40 mol % and is thus inadequate.
Patent Document 1: JP-A-59-222429
Patent Document 2: JP-A-4-217928
Patent Document 3: US-A-2003-139635
Non-Patent Document 1: Applied Catalysis A: General 218 (2001), 241-250 In the prior art known processes, the yield of propylene, based on the number of moles of the raw material methanol, is low and accordingly, such process embodiments are inadequate as industrial production processes.